Patent GB-816954-A (GB)
Title: Method of and machine for manufacturing curved structural parts of sheet metal
IPC: B21D5/14
Filed: 1955-11-01
Abstract: 816,954. Straightening and curving; making railway carriage roofs. UNGERER, F. Nov. 1, 1955, No. 31200/55. Classes 83 (2) and 83 (4). A method of making sheet metal structural parts having a predetermined curvature which varies in the direction of its length, makes use of a straightening machine having top and bottom groups of rollers which rollers or at least a roller at the delivery end of the machine are adjusted while the sheet is passed through so as to effect the bending of the sheet as it leaves the machine to the required curvature. A metal sheet is passed between groups of straightening rollers 1 and 2, the last roller 2<SP>1</SP> of the group 2 being adjustable toward the rollers 1, Fig. 1, to effect the curving of the sheet as it leaves the rollers. Alternatively, or additionally, the roller 2<SP>1</SP> may be adjusted in the feed direction to or from its adjacent roller 2 and the last roller 1<SP>1</SP> adjusted to or from its adjacent roller 1 twice the displacement of the roller 2<SP>1</SP> to effect the curving. The roller 21 may be displaced a different amount at one end from the other, giving the sheet a conical form. The plane of the rollers of the top group may be tilted with respect to those of the bottom group, the intersection of the planes lying on the delivery side of the machine, Fig. 7, to effect the curving. To form a roof for a railway wagon, a metal sheet is fed through the machine with the groups of rollers tilted so that their planes intersect of the entry side of the machine to form a flat part 30 at the end of the sheet. The top group of rollers is then tilted the other way, Fig. 7, so that the sheet is curved at 31, this tilting being gradually reduced to increase the radius of curvature at 32, Fig. 8. With the roller groups not tilted the rest of the sheet is passed through, the direction of rotation of the rollers is then reversed and the curving effected at the other end of the sheet. The top group of rollers is then raised so that the bent sheet may be removed. The sheets may be marked at predetermined points so that it may be seen when to change the degree of tilt or the tilting may be automatically controlled by cam means. Two pairs of groups of rollers may be used. The rollers 1, 2 may be mounted in frames 4, 3, Fig. 4, and backed by supporting rolls 6, 5 distributed along the rollers 1, 2 and arranged in holders 8, 7. The top group of rollers is inclined by means 10 and a vertically movable carriage 9. In a modification, Fig. 5, a vertically slidable carriage 13 supports rollers 14 backed by rolls 16 in holders 17 rigid with the carriage. Lower rollers 15 are supported by rolls 16 in holders 17 running in the direction of the sheet feed which are displaceable to incline the group of rollers 15. The rollers 14 are driven through telescopic shafts and universal joints. The holders 17 may be in sections each carrying two support rolls individually adjustable so that the rollers lie in a curved surface rather than a plane. The rollers may be arched along their length. The rollers may have profiles varying along their length or the groups of rollers may be inclined to each other in the direction of the length of the rollers.